Several biologically originating metal sequestration agents are known in the art. Examples of such agents include tannins, humic acid, whole cell biomass, chitin and chitin derivatives, metallothioneins, microbial polysaccharides, melannins, polyphenolic biopigments, bacterial cell wall polymers, microbially produced chelating agents (siderophores), and the like. However, the above materials may be costly and often are not available in sufficient quantities. Specifically, the substances known in the art have not been successfully produced on large scale for industrial use because of the low availability of raw materials and the high production costs.
Furthermore, the substances known in the art may be less effective than the agropolymer disclosed herein. Thus, the present invention is aimed at producing agropolymers, which are effective in sequestering metals and ions from polluted or contaminated aqueous solutions and which derive from inexpensive, widely available plant materials, preferably raw agricultural materials, such as seed coats, hulls, husks, or seed covers of agricultural crops.